The present invention generally relates to a waterproof construction of wires in a wiring harness for a motor vehicle and more particularly, to a construction which is capable of easily waterproofing wires connected to a terminal attached to a location which droplets hit directly or a terminal to be mounted on a nonwatertight connector.
As shown in FIG. 1, water is likely to be directly splashed on a wiring harness W disposed in an engine room of a motor vehicle. Especially, in case a terminal (LA terminal) T connected to a wire of the wiring harness W is directly bolted to a body panel or the like or a terminal is mounted on a nonwatertight connector C, water is apt to penetrate among strands of wires connected to these nonwatertight terminals by capillarity. Water which has penetrated into the wires proceeds to a cabin as shown by the arrows in FIG. 1 and reaches connectors (not shown) provided in the cabin, thereby resulting in corrosion of terminals accommodated in these connectors.
Conventionally, in order to prevent the above mentioned penetration of water through the wires, it has been proposed that waterproofing is performed as shown in FIG. 3 at branch points P-1 and P-2 where branch wires W2 and W3 branch off from a main wire W1 connected to the nonwatertight terminal T as shown in FIG. 2. In this waterproofing, coatings of the main wire W1 and the branch wires W2 and W3 are partially peeled at the branch points P1 and P2. Then, peeled portions of the wires W1 to W3 and portions of the wires W1 to W3, which are disposed upstream and downstream of the peeled portions of the wires W1 to W3, are wrapped in a doubled waterproof film 4 such that the wires W1 to W3 are embedded in sealing compound 5 sticking to an inner surface of the waterproof film 4. Subsequently, another waterproof film 6 is wrapped around the waterproof film 4.
However, in this known waterproofing method, all the branch points should be waterproofed, which is troublesome. Furthermore, since waterproof materials used for this known method, for example, silicone, butyl rubber, etc. are expensive, waterproofing cost rises due also to increase of the number of portions requiring waterproofing. Meanwhile, since the waterproof material is filled only between the wires, it is impossible to prevent water from penetrating among strands of the wires from the terminal T by capillarity. Furthermore, when the above mentioned waterproofing has been performed, the waterproofed portion swells. As a result, such drawbacks are incurred that the waterproofed portion cannot be inserted into a corrugated tube, a clip cannot be attached to the waterproofed portion by circumferentially winding the clip around the waterproofed portion and the waterproofed portion cannot be inserted into the protector.
Alternatively, as shown in FIG. 4, it has been proposed that a waterproof sheet 7 in which sealing compound 5' is applied to a butyl rubber sheet or the like is wrapped around a contact bonding portion between a wire W1 and a terminal T. However, in this known method, the contact bonding portion around which the waterproof sheet 7 is wound swells. Thus, as shown in FIG. 5, when a nut N is screwed onto a bolt B by inserting the bolt B through a bolt hole of the terminal T, it is difficult to obtain sufficient clamp area required for screwing the nut N onto the bolt B.
Furthermore, such a countermeasure as shown in FIG. 6 is known in which the wiring harness W is enclosed by a protector 8 so as to prevent water from being splashed on the wiring harness W in the directions of the arrows. However, when water is splashed on the terminal T even if the wiring harness W is covered by the protector 8, water is sucked up from the terminal T by capillarity as described above and thus, it is impossible to prevent water from penetrating among strands of the wire.
Therefore, as shown in FIG. 7, if a portion 9 for mounting the terminal T thereon is also enclosed by a protector 8' in addition to the protector 8 for the wiring harness W and the terminal T is provided on an inner vertical wall face of the protector 8', it is possible to prevent droplets from being directly splashed on the terminal T. However, in this case, the protector 8' becomes large in size, thereby resulting in rise of waterproofing cost. Furthermore, in view of efficiency for mounting the terminal T on the portion 9, it is preferable that the wire is as long as possible. However, in this case, an excess portion of the wire is produced and thus, the wire hangs downwardly. On the contrary, when the wire is shortened, efficiency for mounting the wire on the portion 9 drops undesirably. Moreover, if the portion 9 is covered by the protector 8', an operator readily fails to mount the terminal T on the portion 9 and the terminal T is likely to be fastened to the portion 9 insufficiently.
In addition, in case a terminal is mounted on a nonwatertight connector, penetration of water into a wire from the nonwatertight connector can be prevented by covering the nonwatertight connector by a rubber boot or simply injecting grease, etc. into a terminal receiving portion of the nonwatertight connector. However, when the nonwatertight connector is covered by the rubber boot, waterproofing cost rises and it becomes difficult to couple the connector and a mating connector with each other. Meanwhile, in the above mentioned another prior art waterproofing method in which grease is injected into the terminal receiving portion of the connector, such a problem arises that due to change of quality of grease with time, grease is washed away from the terminal receiving portion by rainwater or splash from a road surface.